Justin Bieber (Fighting/Making Threats)...#HeGangsta

Selena Gomez may be firing zingers at Justin Bieber, but he's not planning to blast back -- and he's put his pals on notice that they'd better not say anything about her, either.

According to Perez Hilton, the Bieb has laid down the law and told his entourage to leave Selena alone. A source says, “She’s been bashing him, but Justin has ordered everyone around him not to retaliate. He doesn’t want to fuel the fire and he just doesn’t want it to be that way with her. ‘I don’t want anyone saying anything negative about her,’ is what he told his pals.”

Also in Justin Bieber News - He got into a scuffle with a neighbor that could lead to a serious battery charge.

The two men got into an argument on the boundary of their properties in Calabasas, California this morning (Tuesday), and according to the unnamed neighbor, Justin got physical and threatened the man with harm. But Justin's peeps say the guy walked into Bieber territory and began screaming about loud parties that took place while he was on tour.

The Los Angeles County Sheriff's Department is trying to unravel the tangled mess.